1. Field of the Art
This invention relates to an ultrasound endoscope which is capable of both endoscopic and ultrasound examinations in body cavities, and more particularly to an ultrasound endoscope which is arranged to facilitate maintenance and service such as inspection, repair and replacements of internal component parts within a rigid tip end section at the distal end of an insertion instrument of an ultrasound endoscope.
2. Prior Art
Generally, ultrasound endoscopes are provided with an endoscopic observation means including an illumination window and an observation window on a rigid tip end portion at a distal end of an elongated insertion instrument along with an ultrasound examination means such as an ultrasound transducer. After introducing the insertion instrument into a body cavity, an intracavitary site of interest is firstly examined by the endoscopic observation means, and then the ultrasound examination means is used to further examine tissues in a diseased portion or a suspicious portion which has been spotted as a result of the endoscopic examination. In many cases, the so-called biopsy channel is provided in and through the endoscopic insertion instrument for forceps or a high frequency surgical or biopsy instrument to be introduced into a body cavity and operated under observation through the endoscopic observation means or for a puncture needle or other puncture instrument to be operated under observation through ultrasound scan images.
Connected to the base end of the insertion instrument of the ultrasound endoscope is a manipulating head assembly to be gripped by an operator at the time of endoscopic or ultrasound examination. Various operation control buttons and levers are provided on the manipulating head assembly. The insertion instrument has an elongated flexible body which can be bent easily along the shape of a path of insertion, and an angle section and a rigid tip end section are successively connected to the fore end of the elongated flexible body. The above-mentioned endoscopic observation means, ultrasound examination means and biopsy channel are provided on the rigid tip end section. Accordingly, by operating the manipulating head assembly to turn the angle section in an upward, downward, rightward or leftward direction, the rigid tip end section can be turned into an arbitrary direction.
As described above, the endoscopic observation means, ultrasound examination means and biopsy channel are mounted on the rigid tip end section which constitutes a distal end portion of the endoscopic insertion instrument. The ultrasound transducer which constitutes an ultrasound scan means is classified into either a mechanical scan type or an electronic scan type depending upon scan mode. In the case of an electronic scan type, the ultrasound transducer is constituted by a large number of transducer elements which are arrayed in a predetermined direction. At the time of an electronic scan, the transducer elements are driven successively one after another or transducer elements in a number of transducer element groups are successively driven to obtain echo signals.
On the other hand, the endoscopic observation means is largely composed of an illumination window in which a light emitting end of an illumination light guide is located, and an observation window in which a lens tube of an optical objective lens system is mounted. A solid-state image sensor device (or a light incident end of an image light guide) is located at the focus of the optical objective lens system. The optical objective lens system and the solid-state image sensor device are assembled together and provided as an image pickup assembly unit. Further, a biopsy channel, i.e., a passage for biopsy and surgical instruments, is generally constituted by a flexible tube which is bendable within the flexible body portion and angle section of the insertion instrument. A passage way leading to an outlet opening of the biopsy channel is bored through the rigid tip end section at the distal end of the insertion instrument. A connector pipe is fitted in the outlet passage way and a fore end portion of the flexible biopsy channel tube is connected to a base end of the connector pipe which is projected by a predetermined length from the proximal end of the rigid tip end section.
In laying out the various component parts of the endoscopic and ultrasound examination means on the rigid tip end section at the fore distal end of the insertion instrument, it has been known in the art to locate the ultrasound transducer at the distal end of the rigid tip end section, with ultrasound transducer elements arrayed in a convexly curved shape in the axial direction of the rigid tip end section. The observation window of the endoscopic observation means is provided in a sloped surface rising gradually upward toward the rear end of the rigid tip end section from the proximal end of the ultrasound transducer mount portion. Illumination windows are provided on the opposite lateral sides of the observation window. The biopsy channel is opened at a position between the ultrasound transducer mount portion and the observation window of the endoscopic observation means. Ultrasound endoscopes having the component parts of the endoscopic and ultrasound examination means laid out in this manner are known in the art, for example., from Japanese Laid-Open Patent Application 2002-238906.
In connecting a rigid tip end section to an angle section of an endoscopic insertion instrument, it is usually the case to connect the rigid tip end section separably to the angle section which is constituted by a series of flexibly connected rings. For this purpose, a foremost ring of the angle section is fitted and fixed on a proximal end portion of the rigid tip end section. An outer skin layer of the angle section is extended to a position beyond and forward of the foremost ring, and securely fixed on the rigid tip end section by line wrapping and an adhesive agent. The reason why the rigid tip end section is separably connected to the angle section is to make the maintenance and service of the component parts of the endoscopic and ultrasound examination means feasible, that is to say, to permit inspection, repair and replacements of internal component parts of the rigid tip end section.
In this regard, as already mentioned hereinbefore, an ultrasound transducer is mounted on the rigid tip end section. Wires from the respective ultrasound transducer elements on an ultrasound transducer assembly are led out from the transducer assembly and passed through the angle section and the elongated flexible main body portion of the insertion instrument and connected to corresponding wiring members in the manipulating head assembly of the endoscope. Further, signal lines of the endoscopic observation means, that is to say, signal lines which are connected from the solid-state image sensor device and led out from the image pickup assembly unit are also passed and extended through the angle section and the flexible body portion of the insertion instrument along with a bundle of fiber optics of the light guide which transmits illumination light to the illumination windows. Furthermore, a tube which serves as a biopsy channel is also passed through the angle section and the flexible main body and extended as far as the manipulating head assembly of the endoscope.
Generally, in the case of an ultrasound endoscope with an electronic scan type ultrasound transducer, it is the ultrasound transducer which is most expensive among the various component part which make up the ultrasound endoscope. Nevertheless, it has been extremely difficult to repair the ultrasound transducer when it is damaged or in the event of malfunctioning. That is to say, it has been virtually impossible to carry out maintenance and service on the ultrasound transducer. In contrast, it is relatively easy to replace the solid-state image sensor device and its wiring, the light guide and the biopsy channel tube when damaged.
Therefore, when the rigid tip end section is detached from the angle section, the jobs of maintenance and service have been limited to the solid-state image sensor device and its wiring, the light guide and the biopsy channel tube. Above all, internal surfaces of the biopsy channel tube are susceptible to damages since the biopsy channel is often used for insertion of puncture instruments with a sharp-pointed puncture needle. Further, breakage could occur to the signal lines from the solid-state image sensor device.
In order to enhance the resolution of ultrasound images, it is necessary for an ultrasound endoscope with an electronic scan type ultrasound transducer to increase the number of ultrasound transducer elements and to use a wiring system involving a considerably increased number of wiring connections. Therefore, when the rigid tip end section is detached and pulled away from the angle section to repair or replace a certain component part, difficulties are often encountered in separating the repairing or replacing component part from other component parts which are densely packed in the rigid tip end section of the insertion instrument. Therefore, it has been extremely difficult and troublesome to inspect, repair or replace a particular component part separately from other densely packed component parts, without damaging other component parts. Especially, in case the ultrasound transducer and the wiring to the transducer are made detachable or separable from the rigid tip end section to facilitate maintenance and service jobs on component parts other than the ultrasound transducer and its wiring, the construction of the rigid tip end section will become too complicate and will become a great obstacle to the maintenance and service.
Besides, at the time of relocating an image pickup assembly unit on the rigid tip end section of the insertion instrument, it is necessary to adjust its position in the rotational or radial direction. Further, regarding the biopsy channel, the biopsy channel tube is extended axially through the insertion instrument to a point immediately on the proximal side of the rigid tip end section and connected to a bent connector pipe which is fitted in a forwardly upturned exit passage in the rigid tip end section. Accordingly, the connector pipe has particular directionability in bending direction. It follows that the lens tube of the optical objective lens system as well as the connector pipe has to be securely and firmly fixed in position by application of an adhesive after adjusting its position relative to the rigid tip end section. Therefore, the applied adhesive has to be stripped off to take out the optical image pickup assembly unit and the biopsy channel from the rigid tip end section for maintenance and service. On such an occasion, there are increased possibilities of damaging other component parts which happen to be in the close proximity.